UAV positioning for out-of-band integrated access and backhaul millimeter wave network

Abstract Unmanned Aerial Vehicles (UAVs) can play a major role in enhancing both the access and backhaul networks of the next generation of mobile networks. In this paper, we propose a novel positioning scheme that finds the optimum 3-dimensional flying locations for the UAVs to enhance the connectivity of the backhaul network, while providing the desired quality of service (QoS) for the served users in the access network. The backhaul network connectivity is represented by the algebraic connectivity (or Fiedler value), while the user equipments (UEs) signal reception quality is represented by the signal-to-interference-and-noise-ratio (SINR). We consider an out-of-band integrated access and backhaul (IAB) network, in which we consider the interference that is generated from the deployed UAVs within the access network. The formulated UAV positioning problem is modeled as a low-complexity semi-definite programming (SDP) optimization problem, which can be solved numerically with low complexity. We also consider the access network to experience the propagation modeling of millimeter wave (mm-wave) frequency band. Finally, computer simulations are conducted to show the improvement of the proposed algorithm, in terms of the backhaul algebraic connectivity, while guaranteeing the desired SINR threshold for all the UEs in the access network.